Over the past decade considerable attention has been given to development of micro-optic lens arrays (MLA). Micro-optic lens arrays (also referred to as micro-lens arrays) have applications in many areas of optics, fiber communications and optical interconnects. With advances in dense wavelength division multiplexing (DWDM) networks, the need for multi-channel beam collimation and focusing has grown steadily. MLA structures may be employed for three-dimensional (3D) light beam collimation, for example, in 3D fiber array to fiber array connections or 3D microelectronic mechanical (MEM) optical switches. Two dimensional (2D) MLAs with light beam collimation, built using planar lightwave circuit (PLC) technology, are also widely used for planar optical devices. PLC devices have already occupied a prominent place in tele- and data communication systems, for example, monolithic and hybrid integration approaches have been developed or proposed for a number of active and passive networking devices such as multiplexers and demultiplexers, filters, attenuators, transceivers, switches, etc. In addition, 2D and 3D light guiding structures have been developed or proposed for low loss transmission of confined light modes.
Single mode transmission channel waveguides are typically used in DWDM networking devices. However, in such devices collimated beams are sometimes expected to propagate rather long distances without confinement in the direction parallel to the surface and perpendicular to the beam propagation. For such systems, 2D micro-optical lenses are required to collimate or focus the light in the lateral domain while the three layer waveguiding structure confines light in the vertical direction.
There is an overall need for tunable devices for use in photonic networks. The characteristics of optical devices and optical fibers may vary in use, depending on conditions such as ambient temperature, electromagnetic fields, and light wavelength. In order to minimize induced distortions it would be valuable to include tunable elements into such networks so that they can compensate for the variations of the other parameters. In case of micro-lenses, the tunability is also desirable because of the different paths that light can travel after exiting the lens. For example, in a non-blocking cross-connect switching device the light propagates very different distances for “off” and “on” states.